Soap



UNITED STATES Cross Reference PATENT OFFICE SOAP Richard Thomas and Henry Bowen Oakley,

Bromborough, England,

assignors to Lever Brothers Company, a corporation of Maine No Drawing. Application March 22, 1938, Serial No. 197,376. In Great Britain March 24, 1937 3 Claims.

This invention relates to improvements in soap products.

It is well known that when soap is dissolved in hard water it reacts with the calcium and magnesium salts present to an extent depending upon the degree of hardness of the water. The soap which so reacts becoms insoluble and is rendered inactive for the purpose of washing. The insoluble soaps are liable to form a scum particularly when the water is heated and are deposited in a greater or less degree on clothes washed in the water.

It is an object of the present invention to obtain a soap product which can be dissolved in hard water without substantial precipitation of insoluble soaps and formation of scum.

Other objects and advantages of the invention will become apparent from the following description.

The invention in general is based on the discovery that when soaps derived from polyethylenic fatty acids, i. e. fatty acids having two or more ethylenic groups, such as linoleic acid, for example, or from mixtures of polyethylenic fatty acids with other fatty acids in certain limiting proportions, are incorporated with phosphates of the alkali metals, the resultant products when dissolved in hard water give rise to little or no precipitation of insoluble soaps or formation of scum.

The invention consists in a process for the manufacture of soap products which comprises incorporating orthophosphates of the alkali metals, e. g., trisodium or tripotassium phosphate or disodium or dipotassium monohydrogen phosphate or mixtures thereof, with soaps and producing the products in a form in which they will rapidly dissolve in water, the soaps being derived from ifill l filli s atlxaai a linoleic, linoleni, clupanodonig, or from mixtures of such fatty acids, with monoethylenic fatty acids, e. g., oleic, pahnitglgic, erucic, or from such fatty acids or mixtiires there' dl' with limited proportions of saturated fatty acids, e. g., stearic; palmitic, myristic. The trisodium and tripotassium phosphates and the disodium and dipotasslum monohydrogen phosphates mentioned above are all well known to have an alkaline reaction in solution.

According to the invention, the soaps may be derived from polyethylenic fatty acids, or monoethylenic fatty acids or mixtures thereof, and saturated fatty acids such as stearic and palmitic acids, provided the latter two acids which have a relatively high molecular weight are present in quantities not exceeding about 18% and 25% respectively, and their total percentage does not exceed about 25% of the total fatty acid mixture. In addition, the mixture of fatty acids may also comprise saturated fatty acids of lower molecular weight, such as lauric and myristic acids, but the total quantities of saturated fatty acids should apparently not exceed limits varying between 30-40% of the total mixture, the permissible limits for desirable results in any par ticular case depending upon'the quantities of the stearic and palmitic acids present, in the sense that the lower the proportions of the latter. acids the larger can be the total proportions of saturated acids. In other words: if the mixture of fatty acids contains large quantities of stearic and palmitic acids, say 18% of the former or of the latter, then the lauric and myristic acids for best results may only be present in comparatively small proportions bringing the total quantities of saturated fatty acids up to not more than about The total quantities of saturated fatty acids may, however, be increased up to 40% if the stearic or palmitic acids or both form only a small percentage, say less than about 10%, of the mixture of fatty acids.

The proportion of polyethylenic fatty acids required in the fatty acid mixture to ensure that the product will have the desired properties has been found to vary considerably with the nature of the other fatty acids present. Thus, if oleic acid should be the only other acid present a relatively small proportion of linoleic acid suffices, satisfactory results having been obtained with a mixture of of oleic acid and so little as 5% of linoleic acid. 0n the other hand, the high molecular saturated fatty acids, 1. e., stearic and palmitic acids, when used in larger quantities tend to have an adverse effect upon the properties of the soap product, and the presence of substantial proportions of such saturated acids requires the use of larger quantities of linoleic acid. The adverse efiect is considerably less in the case of saturatedacids of lower molecular weight, such as lauric and myristic acids. As a general rule it can be said that the quantities of linoleic acid which are required to obtain the beneficial results of this invention are proportionate to the quantities of the saturated fatty acids present and to the molecular weight of these fatty acids. Thus, for desirable results it is preferred that a fatty acid mixture including, for example, 20% of palmitic and stearic acids should not contain less than about 10% of linoleic acid. Of course, larger amounts of unsaturated fatty acid soaps Examinmay be used than the minimums disclosed herein, the increased amount being controlled primarily by the characteristics desired in the final soap product.

The proportion of phosphates to be incorporated is to some extent dependent upon the composition of the soap and may also vary according to the nature of the product desired. For example, in utilizing phosphates of the type of hydrated disodium-monohydrogen phosphate (Na2HPO4JZI-I2O), or hydrated trisodium phosphate (Na3PO4.12I-IzO), or of a mixture thereof, good results have been obtained with a ratio of about one part to every three parts of the fatty acids, but satisfactory products have also been prepared with larger or smaller proportions of phosphates. As a general rule, the ratio between fatty acids and orthophosphates, for example, calculated as the anhydrous salts, may vary from about 15:1 to about 3.5:1, but should preferably be kept within the limits of 8:1 to 1.

Other ingredients which do not adversely affect the properties of the soap-phosphate mixture may, of course, be added to it, such as, for example, sodium chloride, sodium sulphate, sodium borate or sodium acetate. A suitable proportion of rosin also may be included in the fatty acid mixtures.

The soap products are produced in a finely divided form, such as powder, flakes, threads, parings, puffed granules or the like to ensure rapid solution in water.

Examples (1) To eighty parts of molten soap made from groundnut oil and containing about 63% of fatty acids are added ten parts of hydrated disodiummonohydrogen phosphate (NB.2I'IPO4.IZH2O) and ten parts of hydrated trisodium phosphate (NaaPO4.12H2O) The mixture is sprayed into hot air in the known manner to produce a free-flowing soap powder. (2) To eighty parts of molten soap made from groundnut oil and containing about 63% of fatty acids are added-twenty parts of hydrated disodium-monohydrogen phosphate, and the product is converted into flakes in the known manner.

(3) Fatty acids obtained from a mixture of three parts of groundnut oil and one part of coconut oil are converted into soap. Sixty parts of the soap so obtained, dried to about 85% fatty acid content, are mixed with seven and a half parts of hydrated trisodium phosphate, seven and a half parts of disodium monohydrogen phosphate, twelve and a half parts of sodium perborate and twelve and a half parts of 80 Twaddell neutral sodium silicate, to form a dried powder.

(4) Seventy-five parts of molten soap made from sunflower oil and containing about 63% of fatty acids are intimately mixed with ten parts of hydrated disodium-monohydrogen phosphate, flve parts of hydrated trisodium phosphate and ten parts of sodium chloride, and the product is converted into flakes in the known manner.

Satisfactory products according to the invention have also been obtained with soaps made,

' for example, from olive oil, kapok oil, soya bean oil, commercial oleins, groundnut oil, sunflower oil and other oils containing relatively large proportions of unsaturates. It may be desirable with certain oils to slightly harden them by hydrogenation for the purpose of improving their soap making characteristics but this should be carried out preferably in a manner which produces as little as possible of additional solid saturated acids.

We claim:

1. A soap product having improved hard water characteristics comprising a water soluble soap of a mixture of soap forming fatty acids, said soap forming fatty acids comprising at least about 10% polyethylenic fatty acids, not more than about 20-25% saturated soap forming fatty acids having at least sixteen carbon atoms, and not more than a total amount of about 30-40% saturated soap forming fatty acids, and by weight one part of an alkaline reacting alkali metal orthophosphate calculated as an anhydrous salt to 3.5 to 15 parts of the fatty acids in said soap, said soap product being in a solid flnely divided form to ensure rapid solution in water, whereby said soap product may be dissolved in hard water without substantial precipitation of insoluble soaps.

2. A soap product having improved hard water characteristics comprising a water soluble soap of a mixture of soap forming fatty acids, said soap forming fatty acids comprising at least about 10% polyethylenic fatty acids, not more than about 20-25% saturated soap forming fatty acids containing not less than sixteen carbon atoms, and not more than a total amount of about 30% saturated soap forming fatty acids, and by weight one part of an alkaline reacting alkali metal orthophosphate calculated as an anhydrous salt to 3.5 to 15 parts of the fatty acids in said soap, said soap product being in a solid finely divided form to ensure rapid solution in water, whereby said soap product may be dissolved in hard water without substantial precipitation of insoluble soaps.

3. A soap product having improved hard water characteristics comprising a water soluble soap of a mixture of saturated and unsaturated fatty acids selected from the group consisting of stearic, palmitic, lauric, myristic, monoethylenic and polyethylenic acids in the proportion of at least 10% polyethylenic acids, not more than 18% stearic acid, and not more than 25% palmitic acid, the total amount of stearic and palmitic acids not exceeding 25% and the total amount of the soaps of saturated fatty acids not exceeding 40%. and by weight one part of an alkaline reacting alkali metal orthophosphate calculated as an anhydrous salt to 3.5 to 15 parts of the fatty acids in said soap, said soap product being in a solid flnely divided form to ensure rapid solution in water, whereby said soap product may be dissolved in hard water without substantial precipitation of insoluble soaps.

RICHARD THOMAS. HENRY BOWEN OAKLEY. 

